This application is based on and claims priority from Japanese Application No. HEI 2-327655 filed Nov. 27, 1990, the disclosure of which is incorporated herein.
The present invention relates to a structure of the distal end portion of an electronic endoscope in which a solid-state image pick-up element is contained in the distal end of the insertion portion of the endoscope. In particular, the present invention is a distal end portion of an endoscope having a more compact design than conventional endoscopes.
In a conventional electronic endoscope, a circuit board with electronic circuitry thereon is provided in the vicinity of the solid-state image pick-up element. Lead wires passing through the insertion portion of the endoscope are connected to the electronic circuit so as to provide power, data signals, etc.
FIG. 8 is a perspective view of such a circuit board 101 and associated components. As shown, rectangular prism 103 is disposed at the rear end of objective optical system 102, which extends to the distal side of the insertion portion. An object is imaged on solid-state image pick-up element 104 which is mounted on the circuit board 101, by virtue of reflected light passing through objective optical system 102 and prism 103.
Electronic components 106 are mounted on circuit board 101. The terminals on the rear part of circuit board 101 are soldered to lead wires 107, e.g., as disclosed in Japanese Patent Laid-Open Publication No. Hei. 2-156924.
When lead wires 107 are to be soldered to the rear end portion of circuit board 101, the structure of circuit board 101 must be relatively long so as to provide for terminals. Correspondingly, the rigid part of the distal end of the endoscope is elongated. This makes it difficult to manipulate the endoscope and to insert the same into a body cavity. As a result, some portions of body cavities cannot easily be examined without inflicting pain on a patient.
The electronic circuit wiring portion and the lead wire connecting portion may be arrayed in parallel to each other. However, with such a design, the circuit board dimensions are laterally increased, so that either less space is available for accommodating the surgical instrument channel and other contained members, or the distal end of the endoscope must be designed with a larger diameter. This, of course, also causes limitations as described above.